When environmental noise is checked in accordance with regulations such as noise regulations, a precise noise level needs to be measured by using a sound level meter. In order to measure a precise noise level, a sound level meter must be periodically calibrated. For such calibration, predetermined accuracy is required in terms of legal regulations.
Conventionally, when a sound level meter is calibrated by using a sound calibrator, the sound calibrator is connected to a microphone of the sound level meter, and the amplification magnitude of an amplifier circuit or the like is manually adjusted such that the sound level meter indicates a predetermined value with respect to the sound pressure generated by the sound calibrator.
However, in the conventional calibration method, it is necessary to manually adjust the amplification magnitude of the amplifier or the like of the sound level meter while the sound pressure of the sound calibrator is checked. Therefore, there is a likelihood that the sound pressure for calibration is incorrectly read or the adjustment is incorrectly performed. More specifically, the likelihood of incorrect adjustment becomes high when the calibration is conducted in the measuring field.
Also, the sound pressure generated by the sound calibrator is slightly different even in a case of the same type. The calibration operator needs to read the sound pressure of the individual sound calibrator and adjust the value indicated by the sound level meter with respect to the sound pressure. In addition, even in the case of the same sound calibrator, since the transmission characteristic is different depending on the combination with the microphone of the sound level meter, it is not enough to simply correspond to the sound pressure of the sound calibrator, and thus correction in the sound level meter is needed. In order to perform such correction, it is necessary to review the description of the sound level meter.
The present invention was made to solve the above-mentioned problems of the conventional art, and the object of the present invention is to provide a method and a system for automatically calibrating a sound level meter which achieves accurate and secure calibration of a sound level meter.